The goal of this project is to demonstrate the ability of the nitroxide antioxidant, tempol to oppose irreversible loss of locomotor function due to spinal cord injury (SCI). Presently, only methylprednisolone has been shown to have efficacy in humans for SCI. However, the extent of recovery is limited. Potentially superior countermeasures are available, but require a demonstration of efficacy in an appropriate animal model of SCI before use in patient trials. The proposed studies are based on our preliminary data, in which tempol, which is neuroprotective increased locomotor function following SCI. We will determine the efficacy of treatment with tempol alone and in combination with methylpednisolone or improving locomotor function and sparing spinal cord tissue following chronic injury in an established model of SCI developed by the Multicenter Animal Spinal Cord Injury Study (MASCIS). Optimization of tempol treatment may lead to a therapeutic modality for SCI.